The mighty Columbia, which forms part of the border between Washington and Oregon, drains a huge inland area through the only waterway that crosses the Cascade Mountains
. The area where it accomplishes this feat is now designated the Columbia River Gorge Nat'l Scenic Area
. The river has been harnessed by a series of Dams
for hydroelectric power, irrigation, and transportation. It empties into the Pacific Ocean at Astoria
Major tributaries include the Snake River, which forms part of the Oregon/Idaho border and the Willamette River which empties into the Columbia just above Portland.